Preheat and prep the pan: Heat the oven to 425°F (220°C). Line a large sheet pan with parchment or lightly coat with cooking spray.
Mix the lemon herb marinade: In a small bowl, whisk lemon juice, lemon zest, olive oil, garlic, Dijon (if using), honey (if using), oregano, parsley, 1/2 teaspoon salt, and 1/4 teaspoon pepper.
Season the vegetables: Add potatoes, broccoli, and bell pepper to the sheet pan.
Drizzle with about half the marinade. Toss to coat and spread into an even layer.
Start roasting the veggies: Roast the vegetables for 12 minutes to give the potatoes a head start.
Prepare the salmon: While veggies roast, pat the salmon dry with paper towels. Season with remaining salt and pepper.
Spoon the remaining marinade over the salmon.
Add salmon to the pan: Remove the sheet pan from the oven. Push veggies to the sides and place salmon portions in the center, skin-side down if using skin-on fillets.
Roast to finish: Return the pan to the oven and roast for 8–12 minutes, depending on thickness. Salmon is done when it flakes easily and reaches an internal temperature of 125–130°F for medium or 145°F if you prefer well-done.
Optional broil: For a golden top, broil the salmon for 1–2 minutes at the end.
Keep a close eye on it.
Garnish and serve: Sprinkle with extra parsley and serve with lemon wedges. Portion into containers if meal prepping.